Magnetic element, skyrmion memory, solid-state electronic device, data-storage device, data processing and communication device

ABSTRACT

To provide a magnetic element which can generate a skyrmion, and a skyrmion memory which applies the magnetic element or the like. 
     To provide a magnetic element with a chiral magnet for generating a skyrmion, the chiral magnet is made of a magnetic material having a β-Mn type crystal structure. Also, to provide a magnetic element with a chiral magnet for generating a skyrmion, the chiral magnet is made of a magnetic material having an Au 4 Al type crystal structure.

The contents of the following Japanese patent application(s) areincorporated herein by reference:

-   -   NO. 2014-226235 filed in JP on Nov. 6, 2014, and    -   PCT/JP2015/076538 filed on Sep. 17, 2015,

BACKGROUND 1. Technical Field

The present invention relates to a magnetic element which can generateand erase a skyrmion, a skyrmion memory which uses the magnetic element,a skyrmion memory embedded solid-state electronic device, a datarecording apparatus which incorporates a skyrmion memory, a dataprocessing apparatus which incorporates a skyrmion memory, and acommunication apparatus which incorporates a skyrmion memory.

2. Related Art

A magnetic element which utilizes a magnetic moment of a magnet asdigital information is known. The magnetic element has a nano-scalemagnetic structure which functions as an element of a non-volatilememory which does not need an electrical power when holding information.The magnetic element is expected for applications as a large capacityinformation storage medium due to advantages such as a super-highdensity by a nano-scale magnetic structure, and its importance as amemory device of an electronics device has been increasing.

As a candidate of a next generation type magnetic memory device, amagnetic shift register is proposed mainly by IBM Corp., U.S. Themagnetic shift register drives a magnetic domain wall and transfers itsmagnetic moment disposition by a current, and reads storage information(refer to Patent Document 1).

FIG. 32 is a schematic view showing a principle of driving of magneticdomain wall by a current. A boundary of a magnetic region in which adirection of magnetic moments is opposite to each other is a domainmagnetic wall. In FIG. 32, a domain magnetic wall in a magnetic shiftregister 1 is shown with solid lines. By flowing a current of thedirection of the arrow to the magnetic shift register 1, the magneticdomain wall is driven. By moving of the domain magnetic wall, amagnetism by a direction of the magnetic moment which is located on anupper side of a magnetic sensor 2 changes. The magnetic change isdetected by the magnetic sensor 2 and magnetic information is retrieved.

However, the magnetic shift register 1 like this has a disadvantage thata big current is needed when moving the magnetic domain wall, and atransfer rate of the magnetic domain wall is slow. As a result, writeand erase time of the memory becomes slow.

The inventors of the present invention proposed a skyrmion magneticelement using a skyrmion which occurs in a magnet as a memory unit(refer to Patent Document 2). In this proposal, the inventors of thepresent invention showed that the skyrmion can be driven by a current.

PRIOR ART DOCUMENTS Patent Documents

[Patent Document 1] U.S. Pat. No. 6,834,005

[Patent Document 2] Japanese Patent Application Publication No.2014-86470

[Non-Patent Document 1] Nagaosa Naoto, Tokura Yoshinori, “Topologicalproperties and dynamics of magnetic skyrmions”, Nature Nanotechnology,the United Kingdom, Nature Publishing Group, 2013, Dec. 4, Vol. 8, p899-911.

Because a skyrmion has an ultra-minute magnetic structure with adiameter from 1 nm to 500 nm, and its structure can be held long hours,so expectations for applications for a memory element have beenincreasing. However, as a currently-known chiral magnet which generatesthe skyrmion, there are MnSi, Fe_(1-x)Co_(x)Si, FeGe, andMn_(1-x)Ge_(x)Fe having B20 type crystal structures and the like(Non-Patent Document 1). A maximum temperature to generate the skyrmionin the B20 type crystal structure is 278K (5 degrees Celsius) of FeGe,and is lower than a room temperature 20 degrees Celsius. Therefore, inorder to practically use the skyrmion as a memory element, a crystalstructure of chiral magnet which generates the skyrmion at a temperaturearound a room temperature and is different from the B20 type crystalstructure is needed.

SUMMARY

A first aspect of the present invention provides a magnetic element witha chiral magnet for generating a skyrmion, the chiral magnet is made ofa magnetic material having a β-Mn type crystal structure or an Au₄Altype crystal structure.

A second aspect of the present invention provides a skyrmion memoryhaving a plurality of magnetic elements which are stacked in a thicknessdirection described in the first aspect.

A third aspect of the present invention provides a skyrmion memorycomprising the magnetic element described in the first aspect and agenerating unit of magnetic field which is provided opposite to a chiralmagnet and applies a magnetic field to the chiral magnet.

A fourth aspect of the present invention provides a skyrmion memorycomprising a substrate, a semiconductor element formed on the substrate,the magnetic element described in the first aspect which is stacked onan upper side of the semiconductor element, and a generating unit ofmagnetic field which is provided opposite to a chiral magnet and appliesa magnetic field to the chiral magnet.

A fifth aspect of the present invention provides a skyrmion memoryembedded solid-state electronic device comprising the skyrmion memorydescribed in any of the second aspect to the fourth aspect and asolid-state electronic device within the same chip.

A sixth aspect of the present invention provides a data recordingapparatus with the skyrmion memory described in any of the second aspectto the fourth aspect.

A seventh aspect of the present invention provides a data processingapparatus with the skyrmion memory described in any of the second aspectto the fourth aspect.

A seventh aspect of the present invention provides a communicationapparatus with the skyrmion memory described in any of the second aspectto the fourth aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing one example of a skyrmion which is amagnetic nano-scale texture of a magnetic moment in a magnet. Intensityand direction of the magnetic moment are schematically shown by arrows.

FIG. 2 shows a skyrmion having different helicity γ.

FIG. 3 shows a β-Mn type crystal structure.

FIG. 4 shows a temperature dependency of a magnetization being made of aCo₈Zn₈Mn₄.

FIG. 5A shows a magnetic field dependency of a magnetization of aCo₈Zn₈Mn₄ at 2K.

FIG. 5B shows a magnetic field dependency of a magnetization of aCo₈Zn₈Mn₄ at 50K.

FIG. 5C shows a magnetic field dependency of a magnetization of aCo₈Zn₈Mn₄ at 100K.

FIG. 5D shows a magnetic field dependency of a magnetization of aCo₈Zn₈Mn₄ at 200K.

FIG. 5E shows a magnetic field dependency of a magnetization of aCo₈Zn₈Mn₄ at 300K.

FIG. 5F shows a magnetic field dependency of a magnetization of aCo₈Zn₈Mn₄ at 350K.

FIG. 6 shows a principle of a method for observing a magnetic moment bythe Lorentz electron beam microscopy.

FIG. 7 shows an observed image of a Co₈Zn₈Mn₄ by the Lorentz electronbeam microscopy.

FIG. 8 shows a helical pitch of a Co₈Zn₈Mn₄ by the Lorentz electron beammicroscopy.

FIG. 9 shows an observed image of a Co₈Zn₈Mn₄ in the case of a magneticfield 450 Oe by the Lorentz electron beam microscopy.

FIG. 10 shows a magnetic moment analysis result of an observed image ofa Co₈Zn₈Mn₄ by the Lorentz electron beam microscopy.

FIG. 11 shows a magnetic phase diagram of a skyrmion of a Co₈Zn₈Mn₄.

FIG. 12 shows a temperature dependency of a magnetization of aCo₈Zn₁₀Mn₂.

FIG. 13A shows an observed image of a Co₈Zn₁₀Mn₂ in the case of 345K,applied magnetic field intensity is zero by the Lorentz electron beammicroscopy.

FIG. 13B shows an observed image of a Co₈Zn₁₀Mn₂ in the case of 345K,applied magnetic field intensity is 90 mT by the Lorentz electron beammicroscopy.

FIG. 14 shows a magnetic phase diagram of a skyrmion of a Co₈Zn₁₀Mn₂.

FIG. 15 shows a temperature dependency of a magnetization of aCo₈Zn₉Mn₃.

FIG. 16 shows a magnetic field dependency of a magnetization of aCo₈Zn₉Mn₃.

FIG. 17 shows a differential data of a magnetic field dependency of amagnetization of a Co₈Zn₉Mn₃.

FIG. 18 shows a magnetic phase diagram of a skyrmion of a Co₈Zn₉Mn₃.

FIG. 19 shows a temperature dependency of a magnetization of a Co₁₀Zn₁₀.

FIG. 20 shows a magnetic field dependency of a real part of an acmagnetic susceptibility of a Co₁₀Zn₁₀.

FIG. 21 shows an Au₄Al type crystal structure.

FIG. 22 shows a temperature dependency of a magnetization of a mixedcrystal of a Fe₅Ni₃Si₂ and a Cr₃Ni₅Si₂.

FIG. 23A shows a magnetic field dependency of a magnetization of0.7Fe₅Ni₃Si₂+0.3Cr₃Ni₅Si₂ at 2K.

FIG. 23B shows a magnetic field dependency of a magnetization of0.7Fe₅Ni₃Si₂+0.3Cr₃Ni₅Si₂ at 50K.

FIG. 23 C shows a magnetic field dependency of a magnetization of0.7Fe₅Ni₃Si₂+0.3Cr₃Ni₅Si₂ at 100K.

FIG. 23D shows a magnetic field dependency of a magnetization of0.7Fe₅Ni₃Si₂+0.3Cr₃Ni₅Si₂ at 200K.

FIG. 23E shows a magnetic field dependency of a magnetization of0.7Fe₅Ni₃Si₂+0.3Cr₃Ni₅Si₂ at 300K.

FIG. 23F shows a magnetic field dependency of a magnetization of0.7Fe₅Ni₃Si₂+0.3Cr₃Ni₅Si₂ at 350K.

FIG. 24 shows a configuration example of a skyrmion memory 100.

FIG. 25 shows a configuration example of a skyrmion memory 100.

FIG. 26 shows a configuration example of a skyrmion memory device 110.

FIG. 27 shows a configuration example of a skyrmion memory device 110.

FIG. 28 is a schematic view showing a configuration example of askyrmion memory embedded solid-state electronic device 200.

FIG. 29 is a schematic view showing a configuration example of a dataprocessing apparatus 300.

FIG. 30 is a schematic view showing a configuration example of a datarecording apparatus 400.

FIG. 31 is a schematic view showing a configuration example of acommunication apparatus 500.

FIG. 32 is a diagram showing a principle of driving of magnetic domainby a current.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present invention is described through the embodimentsof the invention. However, the following embodiments do not limit theinvention according to the scope of claim. Also, all the combinations ofthe features described in the embodiments are not necessarily essentialto means provided by aspects of the invention.

One example of a magnet which can generate a skyrmion is a chiralmagnet. The chiral magnet is a magnet having a chiral crystal structure.

The chiral magnet may often become a magnet in which a magnetic momentdisposition when there is no application of an external magnetic fieldis accompanied by a magnetic ordered phase which rotates on a helix withrespect to an advancing direction of the magnetic moment. By applyingthe external magnetic field, a helical magnetic ordered phase changesinto a ferromagnetic phase via a state in which the skyrmion is present.

FIG. 1 is a schematic view showing one example of a skyrmion 40 which isa magnetic nano-scale texture in a magnet 10. In FIG. 1, each arrowindicates the orientations of magnetic moments related to the skyrmion40. The x-axis and the y-axis are orthogonal to each other, and thez-axis is orthogonal to the xy plane.

The magnet 10 has a plane which is parallel to the x-y plane. Magneticmoments that are oriented in every possible direction on the plane ofthe magnet 10 configure the skyrmion 40. In the present example, theorientation of a magnetic field applied to the magnet 10 is the positivez-direction. In this case, the magnetic moments at the outermostcircumference of the skyrmion 40 in the present example are oriented inthe positive z-direction.

At the skyrmion 40, the magnetic moments rotate in a spiral from theoutermost circumference toward the inner side. Furthermore, theorientations of the magnetic moments gradually change from the positivez-direction to the negative z-direction along with the rotation in thevortex manner.

At the skyrmion 40, the orientations of the magnetic moments twistcontinuously between its center and its outermost circumference. Thatis, the skyrmion 40 is a magnetic nano-scale texture having a vortexstructure of magnetic moments. When the magnet 10 in which the skyrmion40 is present is a thin tabular solid material, the magnetic momentswhich configure the skyrmion 40 are in the same direction in itsthickness direction. That is, magnetic moments in the same directionconfigure the skyrmion 40 in the depth direction (z-direction) of theplate from the front surface to the rear surface. A diameter 2 of theskyrmion 40 refers to a diameter of the outermost circumference of theskyrmion 40. The outermost circumference in the present example refersto the circumference formed by magnetic moments which are oriented inthe same direction with the direction of the external magnetic fieldshown in FIG. 1.

A number of skyrmion Nsk characterizes the skyrmion 40 which is amagnetic nano-scale texture having a vortex structure. The number ofskyrmion can be represented by the following [Equation 1] and [Equation2]. In [Equation 2], the polar angle Θ(r) between a magnetic moment andthe z-axis is a continuous function of the distance r from the center ofthe skyrmion 40. The polar angle Θ(r) changes from π to zero or fromzero to π when r is changed from 0 to ∞.

$\begin{matrix}{{Nsk} = {\frac{1}{4}\pi {\int{\int{d^{2}r\; {{n(r)} \cdot \left\lbrack {\left( \frac{\partial{n(r)}}{\partial x} \right) \times \left( \frac{\partial{n(r)}}{\partial y} \right)} \right\rbrack}}}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack \\\begin{matrix}{{n(r)} = \left( {{\cos \mspace{11mu} {\Phi (\phi)}\mspace{11mu} \sin \mspace{11mu} {\Theta (r)}},{\sin \mspace{11mu} {\Phi (\phi)}\mspace{11mu} \sin \mspace{11mu} {\Theta (r)}},{\cos \mspace{11mu} \Theta (r)}} \right)} \\{{\Phi (\phi)} = {{m\; \phi} + \gamma}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

In [Equation 1], the n(r) is a unit vector which shows a direction ofthe magnetic moment of the skyrmion 40 at a location r. In [Equation 2],m is voracity, and γ is helicity. Based on [Equation 1] and [Equation2], when Θ(r) changes from π to zero by changing r from zero to ∞,Nsk=−m.

FIG. 2 is a schematic view showing a skyrmion 40 having differenthelicity γ (Non-Patent Document 1). In particular, one example in casesof the number of skyrmion Nsk=−1 is shown in FIG. 2. FIG. 2(e) shows howthe coordinates of a magnetic moment n are defined (right-handedsystem). Note that because it is a right-handed system, the n_(z)-axisis in a direction from the rear to the front on the surface of the sheetof paper relative to the n_(x)-axis and the n_(y)-axis. In FIG. 2(a) toFIG. 2(e), shading indicates the orientations of magnetic moments.

The magnetic moment indicated by shading on the circumference in FIG.2(e) has a direction on the n_(x)-n_(y) plane. In response to the above,the magnetic moment indicated by the lightest shading (white) of thecircle center in FIG. 2(e) has a direction from the rear side to thefront side of the sheet of paper. The angle relative to the n_(z)-axisof the magnetic moments shown by shading at each location between thecircumference and the center is from π to zero depending on the distancefrom the center. Orientations of each magnetic moment in FIG. 2(a) toFIG. 2(d) are shown by the same shading in FIG. 2(e). Note that like thecenter of the skyrmion 40 in FIG. 2(a) to FIG. 2(d), the magnetic momentindicated by the darkest shading (black) has a direction from the frontof the sheet of paper to the rear of the sheet of paper. Each arrow inFIG. 2(a) to FIG. 2(d) indicates a magnetic moment that is at apredetermined distance from the center of the magnetic texture. Themagnetic textures shown in FIG. 2(a) to FIG. 2(d) are in a state whichcan be defined as the skyrmions 40.

In FIG. 2(a)(γ=0), the shading at the predetermined distance from thecenter of the skyrmion 40 matches the shading on the circumference ofFIG. 2(e). For this reason, the directions of the magnetic moments shownby arrows in FIG. 2(a) are oriented in a radial direction from thecenter to the outer side. The orientation of each magnetic moment inFIG. 2(b)(γ=π) relative to each magnetic moment in FIG. 2(a)(γ=0) is anorientation obtained by rotating each magnetic moment in FIG. 2(a) by180°. The orientation of each magnetic moment in FIG. 2(c)(γ=−π/2)relative to each magnetic moment in FIG. 2(a)(γ=0) is an orientationobtained by rotating each magnetic moment in FIG. 2(a) by −90 degrees(90 degrees clockwise).

The orientation of each magnetic moment in FIG. 2(d)(γ=π/2) relative toeach magnetic moment in FIG. 2(a)(γ=0) is an orientation obtained byrotating each magnetic moment in FIG. 2(a) by 90 degrees (90 degreescounterclockwise).

Note that the skyrmion with the helicity γ=π/2 shown in FIG. 2(d)corresponds to the skyrmion 40 in FIG. 1.

Although the four exemplary magnetic structures shown in FIG. 2(a) toFIG. 2(d) seem different, but are topologically identical magnetictextures.

The skyrmions 40 having structures shown in FIG. 2(a) to FIG. 2(d) are,once generated, stably present, and function as a carrier to conveyinformation in the magnet 10 to which an external magnetic field isapplied.

However, a currently-known chiral magnet alloy which generates askyrmion 40 has been limited to the B20 type crystal structure(Non-Patent Document 1). A magnet which has the highest temperature togenerate the skyrmion 40 among the B20 type crystal structures is FeGe,and is 278K (5 degrees Celsius). As a crystal structure of chiral magnetwhich can generate the skyrmion 40 at the temperature around the roomtemperature 20 degrees Celsius, there are a β-Mn type crystal structureand an Au₄Al type crystal structure.

The β-Mn type crystal structure belongs to P4₁32 or P4₃32 space group,and is different from a B20 type crystal structure which has a crystalstructure of P2₁3 space group. The Au₄Al type crystal structure belongsto a P2₁3 space group, but is different from the B20 type crystalstructure which has the same crystal structure of P2₁3 space group.Next, the fact that a material which has the 3-Mn type crystal structureand a material which has the Au₄Al type crystal structure have a crystalphase of skyrmion which is above zero temperature is shown byimplementation examples.

IMPLEMENTATION EXAMPLE 1

A material which has the β-Mn type crystal structure which is a chiralmagnet has a crystal phase of skyrmion above zero temperature. As achemical compound which is the β-Mn type crystal structure, there is amaterial which is made of a Co_(x)Zn_(y)Mn_(z), and satisfies x+y+z=20and 0≦x, y, z≦20. As a more specific example, there is a Co₈Zn₈Mn₄. TheCo₈Zn₈Mn₄ has a skyrmion crystal at 300K (27 degrees Celsius).

FIG. 3 shows a β-Mn type crystal structure. The β-Mn type crystalstructure is a crystal structure of P4₁32 or P4₃32 space group which hasa chiral (helical) structure. Helical structures of the crystalstructure of P4₁32 space group and the crystal structure of P4₃32 are inmirror symmetrical relation. Helical structural β-Mn type crystalstructure is a cubic structure which has 20 atoms in a unit cell. 20elements are made of eight c-sites having an equivalent spatialdisposition and twelve d-sites having an equivalent spatial disposition.The c-sites are located on the three-fold rotation axis, and the d-sitesare located on the two-fold rotation axis. FIG. 3 shows a β-Mn typecrystal structure which is seen from the [111] direction of a singlec-site, and has a three-fold symmetrical property which 20 elementsrespectively overlap the original crystal locations after rotating with120 degrees with respect to the 111-axis. Every c-site is located on thethree-fold rotation axis.

FIG. 4 shows a temperature dependency of a magnetization of a Co₈Zn₈Mn₄which is a β-Mn type crystal structure. The horizontal axis shows atemperature (K) of a Co₈Zn₈Mn₄, and the vertical axis shows amagnetization (μ_(B)/f.u.). An applied magnetic field H of the presentexample is 1 kOe (oersted). The Co₈Zn₈Mn₄ is a helical magnet in which atransition temperature of helical magnet is around 310K (37 degreesCelsius). A transition temperature of helical magnet is important indetermining a temperature to generate the skyrmion 40. A transitiontemperature of helical magnet is a temperature to transit to a helicalmagnetic phase, and shows a maximum temperature which can generate theskyrmion 40.

FIG. 5A to FIG. 5F show magnetic field dependencies of a magnetizationof a Co₈Zn₈Mn₄. The horizontal axis shows an applied magnetic field H(kOe) which is given to a Co₈Zn₈Mn₄ between −3 kOe to 3 kOe, and thevertical axis shows a magnetization (μ_(B)/f.u.). FIG. 5A to FIG. 5Fcorrespond to cases in which a temperature of the Co₈Zn₈Mn₄ isrespectively 2K, 50K, 100K, 200K, 300K, and 350K. In the case of 2K, themagnetic field dependency of the magnetization has hysteresischaracteristics. In the case in which a temperature which is greaterthan or equal to 50K is given, the magnetic moment shows soft magneticproperties which has a linearity until around 1 kOe with respect to theapplied magnetic field H. These soft magnetic properties are arequirement in order to generate the skyrmion 40. Here, the softmagnetic properties refer to a magnet with a small coercive force. Acoercive force is a magnitude of a magnetic field which is needed foroverturning the magnetization.

FIG. 6 is a diagram for describing a principle of a method for observinga magnetic moment by a Lorentz electron beam microscopy. A Lorentzelectron beam microscopy is a transmission electron beam microscopewhich observes the magnetic moment utilizing the Lorentz force. Due tothe Lorentz force, a magnetic field generated in a sample 11 deflects anincident electron beam. By using a method for analyzing an electronimage by the deflected electron beams described below, an intensity anda direction of the magnetic moment can be observed directly. The Lorentzelectron beam microscopy is one of the few devices which can observe anano-scale magnetic moment directly.

The sample 11 is a thin-plate magnet whose thickness is less than orequal to 100 nm. By making the thickness of the sample 11 to be lessthan or equal to 100 nm, the electron beam accelerated and incident froman upper side of the sample 11 can transmit the sample 11.

The Lorentz electron beam microscopy makes the electron beam incident inparallel from the upper side of the sample 11. A magnetization directionof a magnetic domain of the sample 11 is oriented in a plane directionof the sample 11 like the arrows. Thereby, the Lorentz force isgenerated due to the magnetic field of the magnetic domain, and bendstracks of electron beams. Because an electron beam direction isdifferent depending on a direction of the magnetic domain, adistribution occurs at an electron density which reaches a focussurface. An electron density distribution consists of a black portionwith a high density and a white portion with a low density, and therespective portion shows a domain boundary. In the domain boundary,overturning of black and white is generated in an alternating way, andrespective gaps of the black and white overturning show domains.Thereby, the magnetic domain can be observed. In this manner, theLorentz electron beam microscopy can directly observe an image which isgenerated by projecting the magnetic moment to a two-dimensional plane.If the magnetic moment is a helical structure, the overturning of blackand white can be observed continuously. On the other hand, in a normaltransmission electron beam microscope, an incident electron beam uses afocused beam which has focal points at the sample plane. By sweepingthis converging point on a two-dimensional surface of the sample plane,an atom image of the two-dimensional surface can be obtained. However,electron scattering by the magnetic moment does not receive interferenceeffect, the magnetic moment cannot be observed. Next, a chiral magnetactually observed by the Lorentz electron beam microscopy is shown. FIG.7 shows an image by Lorentz electron beam microscopy of a Co₈Zn₈Mn₄ attemperature 95K, and in which an applied magnetic field H is B=0. Athickness of the sample 11 of the present example is 50 nm. In a [1-10]direction, light and shade of a striped pattern along a [011] directioncan be observed. This striped pattern shows that the magnetic moment ishelically rotated. An actually measured distance from a white region toa white region shows a helical pitch. A region A is any region along the[1-10] direction.

FIG. 8 shows a measurement result of an intensity along the [1-10]direction of the region A in FIG. 7. The horizontal axis shows alocation along the [1-10] direction inside the region A, and thevertical axis shows an intensity of observed signals. In the region A,the intensity is distributed continuously, and a peak is at equalintervals. A peak-to-peak distance is equivalent to a helical pitch.Because the peak-to-peak distance of the present example is 100 nm, thehelical pitch is 100 nm.

FIG. 9 shows an image by Lorentz electron beam microscopy of a Co₈Zn₈Mn₄at temperature 293K (20 degrees Celsius), and in which an appliedmagnetic field H is B=45 mT (450 Oe). The image by Lorentz electron beammicroscopy of the present example shows the state in which the skyrmion40 is generated, and black dots occur. In the case in which the appliedmagnetic field H shown in FIG. 7 is B=0 mT (0 Oe), a dotted image likethis cannot be observed. A black dot shows a hexagonal close-packedcrystal structure which has a six rotational symmetry so as to have aclose-packed structure. A lattice constant of skyrmion crystalcalculated by the image by Lorentz electron beam microscopy of thepresent example matches the numerical value 120 nm, which is determinedby helical pitch 100 nm of a helical magnetic phase with zero magneticfield. From the above, it is found that black dots of the presentexample are crystal lattices made of the skyrmion 40. A diameter of theskyrmion 40 is 120 nm.

FIG. 10 shows a magnetic distribution of the region B (FIG. 9) which isobtained by analyzing the image by Lorentz electron beam microscopy inFIG. 9 using the intensity transport equation method. An arrow whichshows the magnetic moment on a sample 11 rotates clockwise. A length ofthe arrow corresponds to a projective component to the sheet of paper ofa magnitude of the magnetic moment. It is shown that the length of thearrow becomes shorter from a circumferential portion to a centerportion, and the center portion is oriented toward a rear surfacedirection from a front surface being perpendicular to the sheet ofpaper. The sample 11 of the present example generates the magneticmoment in the state of the skyrmion (c) in FIG. 2. Vortex structures ofthe skyrmion 40 of the present example are all in the same direction. Amagnetic distribution is calculated depending on an analysis of theimage by Lorentz electron beam microscopy by the intensity transportequation method. Thereby, details of a structure of the magnetic momentof the skyrmion 40 become apparent. That is, the image by Lorentzelectron beam microscopy ensures that the skyrmion 40 is generated inthe sample 11.

A magnetic moment of the skyrmion 40 can be calculated by using theintensity transport equation method. In the present example, the imageby Lorentz electron beam microscopy in the region B is analyzed and themagnetic distribution of the magnetic moment is calculated by thetransport-of-intensity equation. The magnetic distribution of themagnetic moment can be calculated by the following principle. Themagnetic distribution in the magnet changes a phase of an electronthrough Aharonov-Bohm effect. The magnetic distribution can becalculated from this phase change. A phase difference in two paths is

$\begin{matrix}{{\Delta \; \varphi} = {{- \frac{e}{\hslash}}{\int{B \cdot {dS}}}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

The transport-of-intensity equation calculated by Schroedinger equationby paraxial approximation is shown as follows.

$\begin{matrix}{{\nabla_{\bot}{\cdot \left( {I{\nabla_{\bot}\varphi}} \right)}} = {{- \frac{2\; \pi}{\lambda}}\frac{\partial I}{\partial z}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

Here, an Z-axis direction is an electron beam incident direction.

Ε_(⊥)  [Equation 5]

is an operator on a plane which is perpendicular to the z-axis.From this relationship, a phase φ can be calculated by a rate of changeof an electron beam intensity I in the Z-axis direction,

≢I/≢z   [Equation 6]

Based on a relative equation of the phase φ and the electron beamintensity I (the transport-of-intensity equation), a magneticdistribution is obtained by electron beam intensity measurement.

FIG. 11 shows a skyrmion phase diagram determined by the image byLorentz electron beam microscopy of a Co₈Zn₈Mn₄. A thickness of thesample 11 is 50 nm. The thickness of the sample 11 is important ingenerating the skyrmion 40. It is observed in details in the example ofthe FeGe that the thinner the sample 11 is, the wider the SkX regionwhich shows the crystal phase of skyrmion is (Non-Patent Document 1).The crystal phase of skyrmion (SkX) is present at a range from 260K to300K, the applied magnetic field H is present at a region from 30 mT to130 mT.

IMPLEMENTATION EXAMPLE 2

Next, an implementation example about a Co₈Zn₁₀Mn₂ which is a magnetwhich has the β-Mn type crystal structure, and is Co_(x)Zn_(y)Mn_(z),where x+y+z=20, 0≦x, y, z≦20 is described.

FIG. 12 shows a temperature dependency of a magnetization of aCo₈Zn₁₀Mn₂. The horizontal axis shows a temperature (K) of theCo₈Zn₁₀Mn₂, and the vertical axis shows a magnetization (μ_(B)/f.u.). Anapplied magnetic field H of the present example is 1 kOe. Themagnetization of the Co₈Zn₁₀Mn₂ rapidly decreases at around 350K (77degrees Celsius). The Co₈Zn₁₀Mn₂ is a helical magnet in which atransition temperature of helical magnet is around 350K (77 degreesCelsius). Also, a magnetic field dependency of a magnetization is verysimilar to FIG. 5A to FIG. 5F. The magnetic moment which is greater thanor equal to 50K shows soft magnetic properties which has a linearityuntil around 1 kOe with respect to the applied magnetic field H. Thesesoft magnetic properties satisfy a requirement in order to generate theskyrmion 40.

FIG. 13A and FIG. 13B show images by Lorentz electron beam microscopy ofa Co₈Zn₁₀Mn₂. FIG. 13A shows an image by Lorentz electron beammicroscopy of the Co₈Zn₁₀Mn₂ at temperature 345K, in which an appliedmagnetic field H is B=0 mT. At the image by Lorentz electron beammicroscopy in which the applied magnetic field H is B=0 mT, the skyrmioncrystal lattice is not generated.

FIG. 13B shows an image by Lorentz electron beam microscopy of theCo₈Zn₁₀Mn₂ at temperature 345K, an applied magnetic field H is B=90 mT(900 Oe). In the image by Lorentz electron beam microscopy of thepresent example, it is found that a skyrmion crystal lattice isgenerated. A dotted pattern is the skyrmion 40.

FIG. 14 shows a skyrmion phase diagram determined by the observation byLorentz electron beam microscopy of a Co₈Zn₁₀Mn₂. In the presentexample, the sample 11 is in a thin layer shape having a thickness of 50nm, and a 112-face of the sample 11 is observed. The crystal phase ofskyrmion (SkX) is present at a range from temperature 320K to 350K, theapplied magnetic field H is present at a region from 30 mT to 200 mT.Compared to the case of the Co₈Zn₈Mn₄ shown in FIG. 11, a region of thecrystal phase of skyrmion (SkX) is large. Also, compared to the case ofthe Co₈Zn₈Mn₄, in the case of the Co₈Zn₁₀Mn₂, the region of the crystalphase of skyrmion (SkX) spreads to a high temperature side.

IMPLEMENTATION EXAMPLE 3

Next, an implementation example about a Co₈Zn₉Mn₃ which is a magnetwhich has the β-Mn type crystal structure, and is Co_(x)Zn_(y)Mn_(z),where x+y+z=20, 0≦x, y, z≦20 is described. The Co₈Zn₉Mn₃ is a bulkpolycrystal.

FIG. 15 shows a temperature dependency of a magnetization of aCo₈Zn₉Mn₃. The horizontal axis shows a temperature (K) of a Co₈Zn₉Mn₃,and the vertical axis shows a magnetization (μ_(B)/f.u.). An appliedmagnetic field H of the present example is 1 kOe. The Co₈Zn₉Mn₃ is ahelical magnet in which a transition temperature of helical magnet is325K (52 degrees Celsius). Also, a magnetic field dependency of amagnetization (μ_(B)/f.u.) is very similar to the examples in FIG. 5A toFIG. 5F. The magnetic moment which is greater than or equal to 50K showssoft magnetic properties which has a linearity until around 1 kOe withrespect to the applied magnetic field H. These soft magnetic propertiessatisfy a requirement in order to generate the skyrmion 40.

FIG. 16 shows a magnetic field dependency of a magnetization of aCo₈Zn₉Mn₃. In the present example, a magnetic field dependency of themagnetization at around 300K (306K to 325K) is shown. The horizontalaxis shows an applied magnetic field H (kOe), and the vertical axisshows a magnetization (μ_(B)/f.u.). Each curve corresponds to each ofthe magnetic field dependency of the magnetization in the cases when atemperature is changed by 1K at a temperature range of 306K to 325K.With an increase of an applied magnetic field H, the Co₈Zn₉Mn₃ tends tohave a bigger magnetization. Also, the Co₈Zn₉Mn₃ has a biggermagnetization intensity with decrease in a temperature at around 300K.The magnetization of the Co₈Zn₉Mn₃ has a linearity until around 1 kOewith respect to the magnetic field, and shows soft magnetic properties.

FIG. 17 shows a curve obtained by differentiating a magnetic fielddependency of a magnetization of a Co₈Zn₉Mn₃. The horizontal axis showsan applied magnetic field H (kOe), and the vertical axis shows a valuedM/dH (a.u.) obtained by differentiating a magnetization M with anapplied magnetic field H. Four temperature regions have tendencies ofrespective different differential curves. For example, at a range from311K to 319K, the applied magnetic field H has a dip structure at adifferential value dM/dH at a region from 0.05 kOe to 0.13 kOe. The dipstructure of the differential value dM/dH shows that there was a changeto the magnetic distribution of the Co₈Zn₉Mn₃ due to the generation ofthe skyrmion 40.

FIG. 18 shows a phase diagram of a crystal phase of skyrmion (SkX) of aCo₈Zn₉Mn₃. The phase diagram of a crystal phase of skyrmion (SkX) of thepresent example is calculated from a differential data of themagnetization shown in FIG. 17. At a range from 311K to 319K, a crystalphase of skyrmion (SkX) occurs at a region from external magnetic field0.05 kOe to 0.13 kOe. The sample 11 used in the present example is abulk crystal, not a thin-plate. Because a three-dimensional crystalshape is used, the skyrmion 40 is hardly generated than the case inwhich a thin-plate is used, and a region of the crystal phase ofskyrmion (SkX) is small.

IMPLEMENTATION EXAMPLE 4

Next, an implementation example of a magnet which has the β-Mn typecrystal structure, and is Co_(x)Zn_(y)Mn_(z), where x+y+z=20, 0≦y, z≦20is described. In the present example, a Co₁₀Zn₁₀ is described in thecase x=y=10, z=0. The Co₁₀Zn₁₀ is a bulk polycrystal.

FIG. 19 shows a temperature dependency of a magnetization of a Co₁₀Zn₁₀.The horizontal axis shows a temperature (K) of a Co₁₀Zn₁₀, and thevertical axis shows a magnetization (μ_(B)/f.u.). An applied magneticfield H of the present example is 20 Oe. The Co₁₀Zn₁₀ is a helicalmagnet in which a transition temperature of helical magnet is 460K (187degrees Celsius). Also, a magnetic field dependency of a magnetization(μ_(B)/f.u.) is very similar to example of FIG. 5A to FIG. 5F. Themagnetic moment which is greater than or equal to 50K shows softmagnetic properties which has a linearity until around 1 kOe withrespect to the applied magnetic field H. These soft magnetic propertiessatisfy a requirement in order to generate the skyrmion 40.

FIG. 20 shows a temperature dependency of a real part of an ac magneticsusceptibility [emu/mol] of a Co₁₀Zn₁₀. It is an amount whichcorresponds to a differential amount of the magnetic moment shown inFIG. 17. In the present example, a magnetic field dependency of a realpart of an ac magnetic susceptibility at 446K to 467K is shown. At atemperature range from 451K to 455K, curves which have recesses at arange of an applied magnetic field from 0 to 0.1 kOe are shown. Theskyrmion 40 is present in this region. This is the same as that curveportions which have recesses on differential curves of the magneticmoment in FIG. 17 show the region where the skyrmion 40 is present.

Like the above-mentioned, as shown in implementation examples 1 to 4, amaterial which has a β-Mn type crystal structure has a crystal phase ofskyrmion. In addition, a material group with a transition temperature ofhelical magnet which is above zero temperature is present. As oneexample of that, by satisfying the conditions of Co_(x)Zn_(y)Mn_(z),x+y+z=20, 0≦x, y, z≦20, the crystal phase of skyrmion is present abovezero temperature. Because a material which has a β-Mn type crystalstructure belongs to a P4₁32 space group which is different from theknown B20 type crystal structure, a selection range of a material whichcan generate the skyrmion 40 is widely expanded.

The material which has a β-Mn type crystal structure is a chemicalcompound including the following multiple elements other than a simplesubstance Mn₂₀. For example, the material which has a β-Mn type crystalstructure is a chemical compound which is made of a chemical formulaA_(x)B_(y)C_(z) using multiple elements A, B, and C, and satisfiesx+y+z=20 and 0≦x, y, z≦20. More specifically, Cu_(20-x)Si_(x),Co_(20-x)Mn_(x), Fe_(20-x)Mn_(x), Co_(x)Mn_(y)Ti_(z)(x+y+z=20),Co_(20-x)Zn_(x), Co_(x)Zn_(y)Mn_(z)(x+y+z=20),Al_(x)Fe_(y)Mn_(z)(x+y+z=20), Ge_(20-x)Mn_(x), Mn_(20-x)Ni_(x),Ga_(20-x)Mn_(x), Al_(20-x)Mn_(x), Fe_(20-x)Re_(x),Fe_(x)Re_(y)Mn_(z)(x+y+z=20), Mn_(20-x)Sn_(x),Fe_(w)Ge_(x)N_(y)V_(z)(w+x+y+z=20), Ga_(20-x)V_(x), Au_(20-x)Si_(x),B_(x)Re_(y)W_(z)(x+y+z=20), Mg_(20-x)Ru_(x), Au_(20-x)Nb_(x),Au_(x)Nb_(y)Zn_(z)(x+y+z=20), Ag_(x)Cu_(y)Y_(z)(x+y+z=20),Ag_(x)P_(y)Pd_(z)(x+y+z=20), Ag_(x)P_(y)Pt_(z)(x+y+z=20), andAg_(x)Pd_(y)S_(z)(x+y+z=20) have β-Mn type crystal structures. However,0≦x, y, z≦20.

Also, a mixed crystal between these chemical compounds also has a βMntype crystal structure. For example, a material which has a β-Mn typecrystal structure is a mixed crystal which is a mixed crystalM_(1-d)N_(d) (0≦d≦1) between a material M which is made of a chemicalformula A_(x1)B_(y1)C_(z1) using multiple elements A, B, and C, andsatisfies x₁+y₁+z₁=20 and 0≦x₁, y₁, z₁≦20, and a material N which ismade of a chemical formula A′_(x2)B′_(y2)C′_(z2) using multiple elementsA′, B′, and C′, and satisfies x₂+y₂+z₂=20 and 0<x₂, y₂, z₂<20. Thematerial which has a β-Mn type crystal structure used for the presentembodiment may select a magnet which includes a magnetic element amongthese. Furthermore, if a material in which a transition temperature ofhelical magnet is above 20 degree is selected, the crystal phase ofskyrmion is present above zero temperature.

IMPLEMENTATION EXAMPLE 5

FIG. 21 shows an Au₄Al type crystal structure. The Au₄Al type crystalstructure is a crystal structure of P2₁3 space group which has a chiralstructure. The B20 type crystal structure such as FeGe which has acrystal phase of skyrmion is a crystal structure of P2₁3 space group. Amaterial which has a helical structure Au₄Al type structure has a cubicstructure which is made of 20 atoms in a unit cell. Spatial dispositionsof 20 elements is made of four equivalent a-sites, four equivalenta′-sites, and twelve equivalent b-sites. A-sites and a′-sites arelocated on the three-fold rotation axis. B-sites are not on the rotationaxis. FIG. 21 shows an Au₄Al type crystal structure seen from the [111]direction of a single a′-site. The structure has a three-foldsymmetrical property which 20 elements respectively overlap the originalcrystal locations after rotating by 120 degrees with respect to the111-axis. A-sites and a′-sites are located on the three-fold rotationaxis. Next, an implementation example of a mixed crystal between aFe₅Ni₃Si₂ and a Cr₃Ni₅Si₂ which is an Au₄Al type crystal structure isshown.

FIG. 22 shows a temperature dependency of a magnetization of a mixedcrystal of (1-x)Fe₅Ni₃Si₂+xCr₃Ni₅Si₂ at 0≦x≦0.4.(1-x)Fe₅Ni₃Si₂+xCr₃Ni₅Si₂ (0≦x≦0.4) is a soft magnet which has a widetransition temperature region from around 200K to around 650K. Thisbehavior is ascribable to a helical magnetism. In particular, 0≦x≦0.3where the magnetic transition temperature becomes above 20 degree isimportant.

FIG. 23A to FIG. 23F show magnetic field dependencies of magnetizationof a mixed crystal of (1-x)Fe₅Ni₃Si₂+xCr₃Ni₅Si₂ at x=0.3. FIG. 23A toFIG. 23F correspond to cases in which a temperature is respectively 2K,50K, 100K, 200K, 300K, and 350K. Like a Co_(x)Zn_(y)Mn_(z) shown inimplementation examples 1 to 4, the mixed crystal of(1-x)Fe₅Ni₃Si₂+xCr₃Ni₅Si₂ of the present example shows a linearity withrespect to a magnetic field intensity until 1 kOe, and shows softmagnetic characteristics. Also, because this crystal structure belongsto a crystal structure of P2₁3 space group which shows a helical crystalstructure, so this crystal structure has a crystal phase of skyrmion.Also, because the magnetic transition temperature is above 20 degree,the structure has a crystal phase of skyrmion above 20 degree.

As explained above, a material which has the Au₄Al type crystalstructure has a crystal phase of skyrmion above zero temperature. Forexample, a material which has the Au₄Al type crystal structure is formedby a material which is made of a chemical formula A_(x)B_(y)C_(z) usingmultiple elements A, B, and C, and a configuration ratio of a and b withx+y=a, z=b satisfies 4:1. More specifically, there are Au₄Al, Cu₄Al,Fe_(4-x)Ni_(x)P, Cr_(4-x)Ni_(x)Si, Fe_(4-x)Ni_(x)Si, Ir_(4-x)Mn_(x)Si,Ge_(4-x)Mn_(x)Ge, Cu_(4-x)Sn_(x)Au, V_(4-x)Ga_(x)Au, Ta_(4-x)Ga_(x)Au,Nb_(4-x)Ga_(x)A_(u), Ag_(4-x)Si_(x)Al, and Mn_(x)Ni_(y)Si_(z)(x+y+z=20)for an Au₄Al type crystal structure. Also, a mixed crystal between thesealso has an Au₄Al type structure.

For example, the material which has the Au₄Al type crystal structure isa mixed crystal M_(1-d)N_(d) (0≦d≦1) between a material M which is madeof a chemical formula A_(x1)B_(y1)C_(z1) using multiple elements A, B,and C, and in which a configuration ratio of a₁ and b₁ with x₁+y₁=a₁,z₁=b₁ satisfies 4:1, and a material N which is made of a chemicalformula A′_(x2)B′_(y2)C′_(z2) using multiple elements A′, B′, and C′,and in which a configuration ratio of a₂ and b₂ with x₂+y₂=a₂, z₂=b₂satisfies 4:1. The material which has the Au₄Al type crystal structureused for the present embodiment may be selected from a magnet whichincludes a magnetic element among these. Furthermore, if a materialwhich has a magnetic transition temperature which is above 20 degree isselected, the crystal phase of skyrmion can be present at a temperaturewhich is above 20 degree.

Conventionally, it was only in a B20 type crystal structure such as FeGeand MnSi that presence of a skyrmion crystal lattice was confirmed in anchiral magnet alloy. In the present specification, it is confirmed thata skyrmion crystal lattice is present in a β-Mn type crystal structureand an Au₄Al type crystal structure of a chiral magnet. Furthermore, itis revealed that these skyrmion crystal lattices are present above zerotemperature. It greatly leads to practical development of the skyrmionmemory. The skyrmion memory is a non-volatile memory which can performdata storage at high speed. This is a new great feature, and is clearlydifferent from a conventional memory.

FIG. 24 shows a configuration example of a skyrmion memory 100. Theskyrmion memory 100 saves bit information using the skyrmion 40.

For example, presence or absence of the skyrmion 40 in a magnet 10corresponds to one bit of information. The skyrmion memory 100 of thepresent example comprises a magnetic element 30, a generating unit ofmagnetic field 20, a measuring unit 50 and a power supply for coilcurrent 60.

The magnetic element 30 can generate and erase the skyrmion 40. Themagnetic element 30 of the present example is an element which is formedin a thin layer shape with thickness less than or equal to 500 nm.

For example, it is formed using techniques such as MBE (Molecular BeamEpitaxy) or sputtering. The magnetic element 30 has a magnet 10, acurrent path 12, and a skyrmion sensor 15.

The magnet 10 expresses at least a crystal phase of skyrmion and ahelical magnetic phase depending on a magnetic field to apply. Thecrystal phase of skyrmion refers to a material in which the skyrmion 40may occur in the magnet 10. For example, the magnet 10 is formed bymaterials shown in implementation examples 1 to 4.

The magnet 10 has a structure surrounded by a non-magnetic material. Thestructure surrounded by a non-magnetic material refers to a structure inwhich all directions of the magnet 10 are surrounded by the non-magneticmaterial. The magnet 10 may be formed in a thin layer shape. The magnet10, for example, may have thickness which is approximately less than orequal to ten times of the diameter of the skyrmion 40. Also, at least apart of the magnet 10 is formed as a two-dimensional material. Thetwo-dimensional material refers to a material in which thickness of themagnet 10 is less than or equal to 100 nm, and thickness of the magnet10 is adequately thin with respect to the front surface of the magnet10.

The current path 12 is one example of a skyrmion controlling unit, andcontrols generating and erasing of the skyrmion 40. The current path 12surrounds a region which includes an end portion of the magnet 10 on onesurface of the magnet 10. The current path 12 may be electricallyisolated from the magnet 10 using insulating materials or the like. Thecurrent path 12 of the present example is a circuit for coil currentwhich is formed in a u-shape. The u-shape may be a shape including aright angle like FIG. 3, not only a shape with a round angle. Thecurrent path 12 may not form a region which is closed on the xy plane.Combination of the current path 12 and an end portion may form a regionwhich is closed on a front surface of the magnet 10. The current path 12connects to the power supply for coil current 60 and flows a coilcurrent. By flowing the coil current to the current path 12, a magneticfield is generated with respect to the magnet 10. The current path 12 isformed by non-magnetic metal materials such as Cu, W, Ti, Al, Pt, Au,TiN, AlSi. In the present specification, a region surrounded by thecurrent path 12 is referred to as a coil region A_(C). Also, a coilregion A_(C) in the case where a region surrounded by the current path12 includes an end portion of the magnet 10 is particularly referred toas an end region A. The current path 12 of the present example has aserial conduction path which crosses an end portion of the magnet 10from a non-magnetic material side to a magnet 10 side at least once, andcrosses from a magnet 10 side to a non-magnetic material side at leastonce, on the xy plane. Thereby, the current path 12 surrounds a regionwhich includes the end portion of the magnet 10. Note that a magneticfield intensity in an end region A is Ha.

The skyrmion sensor 15 functions as a magnetic sensor for skyrmiondetecting. The skyrmion sensor 15 detects generating and erasing of theskyrmion 40. For example, the skyrmion sensor 15 is a resistance elementwhich changes a resistance value depending on presence or absence of theskyrmion 40. The skyrmion sensor 15 of the present example is a tunnelmagneto-resistance element (TMR element). The skyrmion sensor 15 has astack structure of a non-magnetic material thin film 151 and a magneticmetal 152 which is in contact with a front surface of the magnet 10 onone surface of the magnet 10.

The magnetic metal 152 comes into a ferromagnetic phase which has anupward magnetic moment due to an upward magnetic field from the magnet10. A measuring unit 50 is connected between the magnet 10 and an endportion on the opposite side to the magnet 10 side of the magnetic metal152. Thereby, a resistance value of the skyrmion sensor 15 can bedetected. A resistance value of the skyrmion sensor 15 when the skyrmion40 is not present in the magnet 10 shows a minimum value, and theresistance value increases when the skyrmion 40 is present. Theresistance value of the skyrmion sensor 15 is determined by aprobability of a tunnel current of an electron of the non-magneticmaterial thin film 151 depending on a direction of the magnetic momentof the magnet 10 and the magnetic metal 152 which comes into aferromagnetic phase. A high resistance (H) and a low resistance (L) ofthe skyrmion sensor 15 corresponds to presence or absence of theskyrmion 40, and corresponds to information “1” and “0” which is storedin a memory cell of information.

The generating unit of magnetic field 20 is provided being opposite tothe magnet 10. The generating unit of magnetic field 20 generates anapplied magnetic field H, and applies perpendicularly to atwo-dimensional plane of the magnet 10, in a direction from a rearsurface of the magnet 10 to a front surface of the magnet 10.

The rear surface of the magnet 10 refers to a surface on the generatingunit of magnetic field 20 side of the magnet 10. Note that in thepresent embodiment only a single generating unit of magnetic field 20 isused. However, if the generating unit of magnetic field 20 is what canapply a magnetic field perpendicularly with respect to the magnet 10,multiple generating units of magnetic field 20 may be used. The numberand the disposition of the generating unit of magnetic field 20 is notlimited to this.

The measuring unit 50 comprises a power supply for measuring 51 and anammeter 52. The power supply for measuring 51 is provided between themagnet 10 and the skyrmion sensor 15. The ammeter 52 measures a currentfor measuring which flows from the power supply for measuring 51. Forexample, the ammeter 52 is provided between the power supply formeasuring 51 and the skyrmion sensor 15. The measuring unit 50 candetect presence or absence of the skyrmion 40 with little electricalpower by using the skyrmion sensor 15 with high sensitivity.

The power supply for coil current 60 is connected to the current path12, and flows a current in a direction shown by an arrow C. The currentwhich is made to flow to the current path 12 generates a magnetic fieldfrom a front surface to a rear surface of the magnet 10 in a regionsurrounded by the current path 12. Because a direction of a magneticfield which a current which is flown to the current path 12 induces isopposite to to a direction of a uniform magnetic field H from thegenerating unit of magnetic field 20, at a coil region A_(C), a magneticfield Ha which is weakened to a front surface direction from a rearsurface of the magnet 10 occurs. As a result, the skyrmion 40 can begenerated in the coil region A_(C). Note that in the case in which theskyrmion 40 is erased, the power supply for coil current 60 may flow acoil current in an opposite direction to the case in which the skyrmion40 is generated. Also, in the case in which multiple current paths 12are provided, multiple power supplies for coil current 60 may beprovided depending on the number of the current paths 12.

FIG. 25 is a schematic view showing a configuration example of askyrmion memory 100. The skyrmion memory 100 stores information byallowing to generate and erase the skyrmion 40 by a current. Forexample, presence or absence of the skyrmion 40 at a predeterminedlocation of a magnet 10 corresponds to one bit of information.

The skyrmion memory 100 of the present example comprises a magneticelement 30, a generating unit of magnetic field 20, a controlled powersupply 61 and a measuring unit 50.

The magnetic element 30 can generate, erase and detect a skyrmion 40 byan applied current. The magnetic element 30 of the present example has amagnet 10, an non-magnetic metal at upstream side 16, a non-magneticmetal at downstream side 17 and a electrode with notch structure 153.The non-magnetic metal at upstream side 16 and the electrode with notchstructure 153 configure a skyrmion sensor 15.

The non-magnetic metal at upstream side 16 is connected to the magnet10. The non-magnetic metal at upstream side 16 is connected to aspreading direction of the magnet 10. In the present example, thespreading direction of the magnet 10 refers to a direction which isparallel to an xy plane. The non-magnetic metal at upstream side 16 mayhave a thin layer shape. Also, the non-magnetic metal at upstream side16 may have the same thickness as the magnet 10.

The non-magnetic metal at downstream side 17 is apart from thenon-magnetic metal at upstream side 16 and connects to the magnet 10.The non-magnetic metal at downstream side 17 may connect to a spreadingdirection of the magnet 10. The non-magnetic metal at upstream side 16and the non-magnetic metal at downstream side 17 are arranged so as toflow a current which is in a direction approximately parallel to the xyplane to the magnet 10 in the case of applying a voltage. Thenon-magnetic metal at upstream side 16 and the non-magnetic metal atdownstream side 17 are made of conductive non-magnetic metals such asCu, W, Ti, TiN, Al, Pt, Au.

The controlled power supply 61 connects to the non-magnetic metal atupstream side 16 and the non-magnetic metal at downstream side 17. Thecontrolled power supply 61 selects any of a direction from thenon-magnetic metal at upstream side 16 toward the non-magnetic metal atdownstream side 17 and a direction from the non-magnetic metal atdownstream side 17 toward the non-magnetic metal at upstream side 16,and flows a current to the magnet 10. The controlled power supply 61applies a current to the magnet 10 in the direction from thenon-magnetic metal at upstream side 16 toward the non-magnetic metal atdownstream side 17 when the skyrmion 40 occurs in the magnet 10. Also,controlled power supply 61 applies a current to the magnet 10 in thedirection from the non-magnetic metal at downstream side 17 toward thenon-magnetic metal at upstream side 16 when the skyrmion 40 which ispresent in the magnet 10 is erased.

The magnet 10 has a position with notch structure 19 in an end portion18. The end portion 18 in the present example is an end portionsandwiched between the non-magnetic metal at upstream side 16 and thenon-magnetic metal at downstream side 17 among end portions of themagnet 10. In a more specific example, the end portion 18 is an upperside end portion of the magnet 10 in the case when the non-magneticmetal at upstream side 16 is arranged on the right side and thenon-magnetic metal at downstream side 17 is arranged on the left side.The position with notch structure 19 is provided being apart from boththe non-magnetic metal at upstream side 16 and the non-magnetic metal atdownstream side 17 in the end portion 18. A non-magnetic material may beprovided inside the position with notch structure 19.

The skyrmion memory 100 uses the skyrmion 40 which occurs by a currentfrom the controlled power supply 61 for an information storage medium.In FIG. 25, a direction of an electron current is shown by an arrow (adirection of a current is opposite to this). By this electron current,the skyrmion 40 can be generated from the position with notch structure19 of the magnet 10.

In the present example, the skyrmion 40 is generated near a cornerportion 24 of the position with notch structure 19. In the presentexample, the corner portion 24 is a corner portion on the non-magneticmetal at upstream side 16 side in a region which projects the mostinside the magnet 10 in the position with notch structure 19. Theposition with notch structure 19 has at least two corner portions in theregion which projects the most inside the magnet 10. The position withnotch structure 19 may have a side parallel to the non-magnetic metal atupstream side 16 and a side parallel to the non-magnetic metal atdownstream side 17. The corner portion 24 may be an end portion of theside parallel to the non-magnetic metal at upstream side 16. Theposition with notch structure 19 of the present example has a squareshape. The magnet 10 surrounds three sides of the position with notchstructure 19. The remaining one side of the position with notchstructure 19 is a straight line which interpolates between end portions18 on the both sides of the position with notch structure 19. In thiscase, the corner portion 24 is a corner portion which is nearer to thenon-magnetic metal at upstream side 16 among the two corner portions atthe leading edge of the position with notch structure 19. However, theshape of the position with notch structure 19 is not limited to asquare. The shape of the position with notch structure 19 may be apolygon. Also, each side of the position with notch structure 19 may notbe a straight line. Also, a leading edge of at least one corner portionof the position with notch structure 19 may have roundness.

The magnet 10 becomes a ferromagnetic phase due to the generating unitof magnetic field 20. For this reason, the magnetic moment in the magnet10 is oriented in the same direction as a magnetic field H. However, amagnetic moment at an end portion of the magnet 10 is not oriented inthe same direction as the magnetic field H, but has an inclination withrespect to the magnetic field H. In particular, near the corner portionof the position with notch structure 19, an inclination of the magneticmoment continuously changes. For this reason, the skyrmion 40 tends tobe generated more in a corner portion of the magnet 10 compared to inother regions, and the skyrmion 40 can be generated by a predeterminedelectron current.

The position with notch structure 19 has at least two corner portionswhose inside corner forms an obtuse angle in the region which projectsthe most inside the magnet 10. Among the corner portions, an insidecorner of the corner portion 24 which is adjacent to the non-magneticmetal at upstream side 16 is greater than or equal to 180 degrees. Also,an inside corner of the corner portion 22 which is adjacent to thenon-magnetic metal at downstream side 17 may also be greater than orequal to 180 degrees. Here, an inside corner of a corner portion in theposition with notch structure 19 refers to an angle on the magnet 10side of the corner portion 24. For example, in the example in FIG. 25,an inside corner of the corner portion 24 which is adjacent to thenon-magnetic metal at upstream side 16 is 270 degrees.

In the case in which the inside corner of the corner portion 24 is 270degrees, a magnetic moment near the corner portion 24 in the state inwhich a current is not applied is closest to a vortex state. For thisreason, in generating of the skyrmion 40, the inside corner of thecorner portion 24 is preferably 270 degrees.

Also, by flowing a current to the magnet 10 from the non-magnetic metalat downstream side 17 to the non-magnetic metal at upstream side 16, adirection of an electron current is opposite to FIG. 25. The electroncurrent in an opposite direction presses the skyrmion 40 to a regionbetween the position with notch structure 19 and the non-magnetic metalat downstream side 17. The region has a width to a degree so as not tomaintain the skyrmion 40. For this reason, the skyrmion 40 can beerased. Here, a width refers to a length in a direction which a currentflows to the magnet 10 (the y-axis direction in the present example). Onthe other hand, a region between the position with notch structure 19and the non-magnetic metal at upstream side 16 has a width to a degreeso as to maintain the skyrmion 40. That is, the region between theposition with notch structure 19 and the non-magnetic metal at upstreamside 16 has a bigger width than a region between the position with notchstructure 19 and the non-magnetic metal at downstream side 17.

Note that the position with notch structure 19 of the present examplehas the electrode with notch structure 153 which is made of anon-magnetic metal and is connected to the magnet 10 in a spreadingdirection of the magnet 10. Also, the non-magnetic metal at upstreamside 16, in addition to functioning as an electrode for generating anderasing of the skyrmion 40, also functions as an electrode in theskyrmion sensor 15. The skyrmion sensor 15 detects generating anderasing of the skyrmion 40. For example, the skyrmion sensor 15 is aresistance element which changes a resistance value depending onpresence or absence of the skyrmion 40.

The electrode with notch structure 153 is in contact with a side whichis opposite to the non-magnetic metal at upstream side 16 in theposition with notch structure 19. Note that as shown in FIG. 25, thewhole position with notch structure 19 may be the electrode with notchstructure 153. The electrode with notch structure 153 sandwiches alocation at which the skyrmion 40 in a stable state is present with thenon-magnetic metal at upstream side 16. In the present example,depending on generating and erasing of the skyrmion 40, a resistancevalue of the magnet 10 between the non-magnetic metal at upstream side16 and the electrode with notch structure 153 changes. A resistancevalue of the skyrmion sensor 15 when the skyrmion 40 is not present inthe magnet 10 shows a minimum value, and the resistance value increaseswhen the skyrmion 40 is present. A high resistance (H) and a lowresistance (L) of the skyrmion sensor 15 corresponds to presence orabsence of the skyrmion 40, and corresponds to information “1” and “0”which a memory cell stores.

The measuring unit 50 is connected to the electrode with notch structure153 and the non-magnetic metal at downstream side 17. The measuring unit50 measures a resistance value of the magnet 10 between the electrodewith notch structure 153 and the non-magnetic metal at downstream side17. A resistance value between the electrode with notch structure 153and the non-magnetic metal at downstream side 17 corresponds to theresistance value of the magnet 10, and changes depending on generatingand erasing of the skyrmion 40. For example, when the skyrmion 40 is notpresent, a spatially-uniform magnetic field H occurs in the magnet 10.On the other hand, when the skyrmion 40 is present, a magnetic fieldapplied to the magnet 10 is not spatially uniform. When a magnetic fieldwhich is not spatially uniform occurs, a conduction electron which flowsin the magnet 10 is scattered by a magnetic moment of the magnet 10.That is, the resistance value of the magnet 10 becomes higher in thecase in which the skyrmion 40 is present than in the case in which theskyrmion 40 is not present.

The measuring unit 50 of the present example has a power supply formeasuring 51 and an ammeter 52. The power supply for measuring 51 isprovided between the electrode with notch structure 153 and thenon-magnetic metal at downstream side 17. The ammeter 52 measures acurrent for measuring which flows from the power supply for measuring51. A resistance value of the magnet 10 can be detected from a ratio ofa known voltage which is applied by the power supply for measuring 51and a current measured by the ammeter 52. Thereby, information that theskyrmion memory 100 saves can be read.

The skyrmion memory 100 having the above-mentioned configurations can beembodied as a magnetic element which can transfer and erase the skyrmion40 in the magnet 10. In this case, the non-magnetic metal at upstreamside 16, the non-magnetic metal at downstream side 17 and the controlledpower supply 61 operate as a skyrmion controlling unit which controlsgenerating, erasing and transferring of the skyrmion 40.

FIG. 26 shows a skyrmion memory 100 which has multiple generating unitsof magnetic field 20. The skyrmion memory 100 of the present example haseight magnetic elements 30 in total from a magnetic element 30-1 to amagnetic element 30-8. The skyrmion memory 100 has four magneticelements 30 on a generating unit of magnetic field 20-1. The skyrmionmemory 100 further has a generating unit of magnetic field 20-2 betweena magnetic element 30-4 and a magnetic element 30-5. Thereby, themagnetic element 30 can keep an intensity of an magnetic field which isreceived from the generating units of magnetic field 20 constant. Thegenerating units of magnetic field 20 may be arranged at appropriateintervals depending on a material of the magnetic element 30 or thelike.

FIG. 27 shows a configuration example of a skyrmion memory device 110which has a semiconductor element. The skyrmion memory device 110 of thepresent example comprises a CMOS-FET 90 which configures the skyrmionmemory 100 and a CPU functionality. The skyrmion memory 100 is formed onthe CMOS-FET 90. The CMOS-FET 90 of the present example has a PMOS-FET91and a NMOS-FET92 which are formed on a substrate 80. The skyrmion memorydevice 110 can have a CMOS-FET 90 which configures the CPU functionalityand the skyrmion memory 100 which is a stacked large-scale non-volatilememory within the same chip. As a result, shortening of the CPUprocessing time and acceleration is achieved, and a CPU powerconsumption can be significantly reduced.

FIG. 28 is a schematic view showing a configuration example of askyrmion memory embedded solid-state electronic device 200. The skyrmionmemory embedded solid-state electronic device 200 comprises a skyrmionmemory 100 or a skyrmion memory device 110, and a solid-state electronicdevice 210. The skyrmion memory 100 or the skyrmion memory device 110 isthe skyrmion memory 100 or the skyrmion memory device 110 described infrom FIG. 24 to FIG. 27. The solid-state electronic device 210 is, forexample, a CMOS-LSI device. The solid-state electronic device 210 has atleast one functionality of writing data to the skyrmion memory 100 orthe skyrmion memory device 110, and reading data from the skyrmionmemory 100 or the skyrmion memory device 110.

FIG. 29 is a schematic view showing a configuration example of a dataprocessing apparatus 300. The data processing apparatus 300 comprises askyrmion memory 100 or a skyrmion memory device 110, and a processor310. The skyrmion memory 100 or the skyrmion memory device 110 is theskyrmion memory 100 or the skyrmion memory device 110 described in fromFIG. 24 to FIG. 27. The processor 310 has, for example, a digitalcircuit which processes a digital signal. The processor 310 has at leastone functionality of writing data to the skyrmion memory 100 or theskyrmion memory device 110, and reading data from the skyrmion memory100 or the skyrmion memory device 110.

FIG. 30 is a schematic view showing a configuration example of a datarecording apparatus 400. The data recording apparatus 400 comprises askyrmion memory 100 or a skyrmion memory device 110, and an input/outputapparatus 410. The data recording apparatus 400 is, for example, amemory device such as a hard disk or a USB memory. The skyrmion memory100 or the skyrmion memory device 110 is the skyrmion memory 100 or theskyrmion memory device 110 described in from FIG. 24 to FIG. 27. Theinput/output apparatus 410 has at least one functionality of writingdata to the skyrmion memory 100 or the skyrmion memory device 110 fromthe outside, and reading data from the skyrmion memory 100 or theskyrmion memory device 110 and outputting to the outside.

FIG. 31 is a schematic view showing a configuration example of acommunication apparatus 500. The communication apparatus 500 refers to,for example, whole devices which have communication functionalities withthe outside, such as mobilephones, smartphones, and tablet typeterminals. The communication apparatus 500 may be portable, or may benon-portable. The communication apparatus 500 comprises a skyrmionmemory 100 or a skyrmion memory device 110, and a communication unit510. The skyrmion memory 100 or the skyrmion memory device 110 is theskyrmion memory 100 or the skyrmion memory device 110 described in fromFIG. 24 to FIG. 27. The communication unit 510 has a communicationfunctionality with the outside of the communication apparatus 500. Thecommunication unit 510 may have a wireless communication functionality,or may have a wired communication functionality, or may have both awireless communication functionality and a wired communicationfunctionality. The communication unit 510 has at least one functionalityto write data received from the outside to the skyrmion memory 100 orthe skyrmion memory device 110, a functionality to send data read fromthe skyrmion memory 100 or the skyrmion memory device 110 to theoutside, and a functionality to operate based on controlling informationwhich the skyrmion memory 100 or the skyrmion memory device 110 stores.

Also, because saving of an electrical power in an electronic device towhich the skyrmion memory 100 or the skyrmion memory device 110 isapplied can also be achieved, prolonging a mounted battery can beachieved. This allows providing a further epoch-making specification tothe user side in a mobile electronic device to which the skyrmion memory100 or the skyrmion memory device 110 is applied. From a personalcomputer, image storage apparatus or the like, any may be available asan electronic device.

Also about communication apparatuses mounting CPU (mobilephones,smartphones, tablet type terminals or the like), because capturing ofimage information, or operations of various large-scale applicationprograms can be achieved at higher speed, and also high-speedresponsibility can be achieved by applying the skyrmion memory 100 orthe skyrmion memory device 110, this allows ensuring comfortable usageenvioronment for the user. Also, because acceleration of image displayto display on a screen or the like can also be achieved, its usageenvioronment can be further improved.

Also, by applying the skyrmion memory 100 or the skyrmion memory device110 to electronic devices such as digital cameras, this allows recordingvideos at mass storage. Also, by applying the skyrmion memory 100 or theskyrmion memory device 110 to electronic devices such as 4K televisionreceivers, this can achieve enhancing the capacity of its image storage.As a result, this allows eliminating the need for connection of anexternal hard disk in a television receiver. Also, the skyrmion memory100 or the skyrmion memory device 110 may be embodied as a datarecording medium, in addition to the case to apply to data recordingapparatuses from hard disks.

Also, with respect to electronic devices such as automotive navigationsystems, by applying this skyrmion memory 100 or the skyrmion memorydevice 110, further high functionalization can be achieved, and thisalso allows storing a larger amount of map information simply.

Also, the skyrmion memory 100 or the skyrmion memory device 110 can beexpected to have a big impact when practically using an self-travelingdevice and a flying device. That is, a complicated controlling processof the flying device, weather information process, improvement ofservice for passengers by providing projected images with highdefinition image quality, in addition, controlling of space aircraftsand recording massive recorded information of observed imageinformation, which gives much knowledge to human beings.

Also, because the skyrmion memory 100 or the skyrmion memory device 110is a magnetic memory, it has a high resistance with respect tohigh-energy particles which fly about in space. The skyrmion memory 100or the skyrmion memory device 110 has an advantage that is largelydifferent from a flash memory which uses an electrical chargeaccompanied by an electron as a storage holding medium. For this reason,it is important as a storage medium such as a space aircraft.

EXPLANATION OF REFERENCES

1 . . . magnetic shift register, 2 . . . magnetic sensor, 10 . . .magnet, 11 . . . sample, 12 . . . current path, 15 . . . skyrmionsensor, 16 . . . non-magnetic metal at upstream side, 17 . . .non-magnetic metal at downstream side, 18 . . . end portion, 19 . . .position with notch structure, 20 . . . generating unit of magneticfield, 22 . . . corner portion, 24 . . . corner portion, 30 . . .magnetic element, 40 . . . skyrmion, 50 . . . measuring unit, 51 . . .power supply for measuring, 52 . . . ammeter, 60 . . . power supply forcoil current, 61 . . . controlled power supply, 80 . . . substrate, 90 .. . CMOS-FET, 91 . . . PMOS-FET, 92 . . . NMOS-FET, 100 . . . skyrmionmemory, 110 . . . skyrmion memory device, 151 . . . non-magneticmaterial thin film, 152 . . . magnetic metal, 153 . . . electrode withnotch structure, 200 . . . skyrmion memory embedded solid-stateelectronic device, 210 . . . solid-state electronic device, 300 . . .data processing apparatus, 310 . . . processor, 400 . . . data recordingapparatus, 410 . . . input/output apparatus, 500 . . . communicationapparatus, 510 . . . communication unit

What is claimed is:
 1. A magnetic element with a chiral magnet forgenerating a skyrmion, wherein the chiral magnet is made of a magneticmaterial having a β-Mn type crystal structure or an Au₄Al type crystalstructure.
 2. The magnetic element according to claim 1, wherein themagnetic material having the β-Mn type crystal structure is made of achemical formula A_(x)B_(y)C_(z) using multiple elements A, B, and C,and satisfies x+y+z=20 and 0≦x, y, z≦20.
 3. The magnetic elementaccording to claim 1, wherein the magnetic material having the β-Mn typecrystal structure is a mixed crystal M_(1-d)N_(d) (0≦d≦1) between amaterial M which is made of a chemical formula A_(x1)B_(y1)C_(z1) usingmultiple elements A, B, and C, and satisfies x₁+y₁+z₁=20 and 0≦x₁, y₁,z₁≦20, and a material N which is made of a chemical formulaA′_(x2)B′_(y2)C′_(z2) using multiple elements A′, B′, and C′, andsatisfies x₂+y₂+z₂=20 and 0<x₂, y₂, z₂<20.
 4. The magnetic elementaccording to claim 2, wherein the magnetic material having the β-Mn typecrystal structure is made of a chemical compound Co_(x)Zn_(y)Mn_(z), andsatisfies x+y+z=20 and 0≦x, y, z≦20.
 5. The magnetic element accordingto claim 1, wherein the magnetic material having the Au₄Al type crystalstructure is made of a chemical formula A_(x)B_(y)C_(z) using multipleelements A, B, and C, and a configuration ratio of a and b with x+y=a,z=b satisfies 4:1.
 6. The magnetic element according to claim 1, whereinthe magnetic material having the Au₄Al type crystal structure is a mixedcrystal M_(1-d)N_(d) (0≦d≦1) between a material M which is made of achemical formula A_(x1)B_(y1)C_(z1) using multiple elements A, B, and C,and a configuration ratio of a₁ and b₁ with x₁+y₁=a₁, z₁=b₁ satisfies4:1, and a material N which is made of a chemical formulaA′_(x2)B′_(y2)C′_(z2) using multiple elements A′, B′, and C′, and aconfiguration ratio of a₂ and b₂ with x₂+y₂=a₂, z₂=b₂ satisfies 4:1. 7.The magnetic element according to claim 6, wherein the magnetic materialwhich has the Au₄Al type crystal structure is a mixed crystal between aFe₅Ni₃Si₂ and a Cr₃Ni₅Si₂.
 8. The magnetic element according to claim 1,wherein the chiral magnet is made of a magnet which is in a thin layershape.
 9. The magnetic element according to claim 8, wherein a thicknessof a portion which is formed as a two-dimensional material of the chiralmagnet is less than or equal to 100 nm.
 10. The magnetic elementaccording to claim 8, wherein the chiral magnet expresses at least acrystal phase of skyrmion and a ferromagnetic phase in which theskyrmion is generated, depending on an applied magnetic field.
 11. Amagnetic element, wherein a plurality of magnetic elements according toclaim 8 are stacked in a thickness direction.
 12. A skyrmion memorycomprising: the magnetic element according to claim 1, and a generatingunit of magnetic field which is provided opposite to the chiral magnetand applies a magnetic field to the chiral magnet.
 13. A skyrmion memoryembedded solid-state electronic device comprising the skyrmion memoryaccording to claim 12, and a solid-state electronic device within a samechip.
 14. A data recording apparatus with the skyrmion memory accordingto claim
 12. 15. A data processing apparatus with the skyrmion memoryaccording to claim
 12. 16. A communication apparatus with the skyrmionmemory according to claim 12.